This invention is directed to a device and a process both of which are utilized in combination with a pin-tumbler lock cylinder of the type which includes a control cylinder for holding the pin-tumbler lock cylinder within a cylinder lock. The device and the process are utilized to determine the size of at least a portion of the pin-tumblers so as to enable convenient cutting of the cuts in a control key utilized for removing said pin-tumbler lock cylinder from the cylinder lock.
For use in large institutions such as hotels, hospitals, schools and the like, wherein it is often necessary to rekey locks at frequent intervals for security or other reasons, a type of cylinder lock has been developed which utilizes a pin-tumbler lock cylinder which is extracted from the main body of the lock utilizing a control key. The purpose behind the use of the control key is to allow for ease of withdrawal of the pin-tumbler lock cylinder to change the individual pins in the lock cylinder in order to rekey the lock.
If one is in possession of a control key, it is a simple matter to remove the pin-tumbler lock cylinder. This is simply done by inserting the control key, rotating it a few degrees to unlock the pin-tumbler lock cylinder from the lock body and then withdrawing the pin-tumbler lock cylinder. Once the appropriate pins have been changed in the pin-tumbler lock cylinder, the lock cylinder is reinserted into the body of the lock and the control key is utilized to lock the lock cylinder to the main body of the lock.
The pin-tumbler lock cylinders of the type described above have a main body cylinder which has a control cylinder nested within it. The control cylinder moves between an unlocked and a locked position with respect to the main body cylinder with a portion of the control cylinder being withdrawn into the main body cylinder in the unlocked position allowing for removal of the pin-tumbler lock cylinder and this same portion extending out of the main lock cylinder so as to lock the totality of the pin tumbler lock cylinder to the cylinder lock body to secure the pin-tumbler lock cylinder in the cylinder lock body. Nested within the control cylinder is a key plug. The key plug in a standard manner is connected to the bolt mechanism of the cylinder lock to lock or unlock the door or other structure to which the cylinder lock is attached.
The key plug rotates within the control cylinder to lock and unlock the cylinder lock as described above. A first shear line thus exists between the key plug and the control cylinder. The control cylinder in turn rotates within the main cylinder body to lock or unlock the pin-tumbler lock cylinder to the cylinder lock body. As such, a further shear line exists between the control cylinder and the main body cylinder.
When it becomes necessary to change the pins in all of the locks in a large structure such as a hotel or the like, it is evident that if one is in possession of the control key, it is extremely easy to remove each of the pin-tumbler lock cylinders, modify the same and then reinsert them into their respective cylinder lock bodies. The control keys, as such, are not in everyday use, but are only used on special occasions when it becomes necessary to rekey one or more locks. Because it is infrequently used and because of a variety of other reasons, too frequently the control key becomes lost or misplaced or otherwise unavailable when it is necessary to rekey one or more of the cylinder locks.
The presence of two shear lines in the above described pin-tumbler lock cylinders make this type of lock very difficult to pick. Even the most highly skilled master locksmith sometimes has a difficult time in picking these locks. It is obvious then, that on any occasion where one of these locks must be picked, upon successful picking of the lock and upon removal of the pin-tumbler lock cylinder, the first order of business is the preparation of a control key. Once a control key is cut, further pin-tumbler lock cylinders can be removed and/or the new control key can hopefully be stored in a safe place for future use.
The above described pin-tumbler lock cylinders generally use six individual pin-tumblers. Each of these is located in a separate pin bore. The individual pin-tumblers normally include no less than three separate pins. These would include at least a driver pin, a control pin and a bottom pin. If the lock is master keyed, the bottom pin would be further subdivided into two or more pins. At a minimum then, at least eighteen pins are utilized, and when master keying is done, which is the normal case for these locks since they are utilized in institutional type buildings or the like, it is not uncommon to have up to two dozen individual pins incorporated into the pin-tumbler lock cylinder. All of the pins utilized have the same diameter. However, when four or five pins are utilized in a particular pin-tumbler, as for instance when utilizing master keying, certain of the individual pins are extremely thin and difficult to manipulate.
Prior to cutting a new control key, every one of the pins comprising each of the pin-tumbler must be measured with a micrometer to determine their thickness. Once the thickness is determined it must be recorded such that upon completion of this task, the locksmith then knows the sizes of each of the pins in each of the pin tumblers and can utilize this information to prepare either a new control key or to rekey the lock. During the disassembly of the pin-tumbler lock cylinder, it is sometimes very easy to mix up the pins. Further, during "micing" of the pine, especially the very thin pins, it is easy to drop the same or make measurement errors.
In order to correctly cut a new control key, the location and size of each of the pins in every one of the pin-tumblers must be known. Having labored to pick and remove the pin-tumbler lock cylinder, if a mistake is inadvertently made in disassembly, measurement or recording of the individual pins, all is for naught, and the locksmith in order to cut a control key must start over again and remove a second lock cylinder must again pick that lock cylinder.